1error[E0596]: cannot borrow `foo` as mutable, as it is not declared as mutable 2 --> $DIR/span-covering-argument-1.rs:5:14 3 | 4LL | let $s = 0; 5 | -- help: consider changing this to be mutable: `mut foo` 6LL | *&mut $s = 0; 7 | ^^^^^^^ cannot borrow as mutable 8... 9LL | bad!(foo whatever); 10 | ------------------ in this macro invocation 11 | 12 = note: this error originates in the macro `bad` (in Nightly builds, run with -Z macro-backtrace for more info) 13 14error: aborting due to previous error 15 16For more information about this error, try `rustc --explain E0596`. 17